Production of the dipotassium salt of a dinitrocyclic ketone



PRODUCTION OF THE DIPQTASSIUM SALT OF A DINITROCYCLIC KETONE Henry Feller, West Lafayette, 'Ind., and James W. Shepherd, Butler, Pa., assignors to Purdue Research Foundation, Lafayette, Ind., a corporation of Indiana No Drawing. Application June 28, 1957 Serial No. 668,628

12 Claims. Cl. 260-586 Our invention relates to the production of dinitrocyclic ketones and more particularlyfit relates to a process for production of a,ok-dinitrocyclic ketones by reaction of a cyclic ketone with an alkyl nitrate in the presence of a potassium t-alkoxide.

In a paper by Wieland et al., Ann, volume/461, page 295 (1928), Chemical Abstracts, volume 22, page 2553, there is described a process for nitration of cyclopentanone and cyclohexanone employing ethyl nitrate .as a nitration agent and alcoholic'potassium ethoxide as the basic catalyst. The process resulted in only very low yields of 2,5- dinitrocyclopentanone and 2,6-dinitrocyclohexanone, such yields being on the order of about 6%.

We have now discovered a process for nitration of cyclic ketones employing alkyl nitrates as, the nitrating agent wherebyexceptionally high yields in the range from 50 to 75%are obtained. Our' new process also provides a method for obtaining :nitro compounds which could previously'be produced only by the Victor'lv'leyer reaction.

This application;is a continuation-in-part of our copending application Serial No. 536,779, filed July 11, 1955, now abandoned.

Our new processconsists essentially of reacting an alkyl nitratewith a cyclic ketonein the presence of a potassium t-alkoxide-employing a non-alcoholic solvent and a temperature below about 10C.. Thedesired dinitrocyclic ketones are produced in the reaction mixture as the potassium salt, and since the dipotassium dinitrocyclic ketones are hygroscopic; and not easily purified, we have'found that we can convert the dipotassium dinitrocyclic ketones to a,m',w,w'-tetrabromo-o;,ot'-dinitroparafiins by reaction of the dipotassium dinitrocyclic ketones with potassium hypobromite. The yield of the tetrabromo compound is quantitative depending upon the dipotassium dinitrocyclic ketone present and the tetrabrorno compound is obtained in crystalline form which can be readily purified by recrystallization. Because of the more favorable characteristics of the tetrabromo compounds which are derived from the dinitrocyclic ketones, and since the yield of the tetrabromo compound from the dinitrocyclic ketones is quantitative, we have obtained all of our data on yields of dinitrocycliciketones .in terms of the yield of the corresponding a,ot,w,w-tetrabromo-a,x-dinitroparafi'in obtained when the dinitrocyclic ketone is reacted with potassium hypobromite.

In carrying out our process, we react a cyclic ketone such as, for example, cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, etc. with an alkyl nitrate such as,'-for example, ethyl nitrate, propyl nitrate, butyl nitrate, etcin the presence of a potassium t-alkoxide such as, for example, potassium t-butoxide, l-methyl-l-ethyl propionoxide, 1,l-dimethylpropionoxide, etc. and a non-alcoholic inert solvent such as, for example, ether, tetrahydrofuran,toluene, hexane, etc; --We prefer 'to react the cycloketone with amyl nitrate in the presence of potassium t-butoxide using tetrahydrofuran as a solvent.

2,868,838 Patented Jan. 13,1959

As indicated above, the presence of alcohol in our reaction mixture is detrimental to the production of the dinitrocyclic ketones desired. The following table shows the results of two experiments carried out in an identical manner, except that in the second experiment, a small amount of tertiary butyl alcohol was added to the reaction mixture. In both experiments, cyclopentanone was reacted with amyl nitrate in the presence of potassium t-butoxide at a temperature of 30 C.

TABLE I Cyclopent-Butyl Yield Expt. No tauone, Alcohol, Percent Moles Moles Yield of 1,1,4,4-tetrabromo-l,4-dinitrobatone.

As indicated above, we carry out our new process at a temperature below about 10 C. and preferably at a temperature of about 30 C. We also prefer to carry 7 out our reaction by first adding the ketone to the base and then adding the alkyl nitrate to the mixture of ketone and poatssium t-alkoxide. Following addition of the ketone to the potassium t-alkoxide, at the preferred temperature of about -30 C., the nitrate is then added to the mixture. As soon as the addition of the nitrate is complete, the reaction mixture is allowed to warm to room temperature. The reaction mixture can be maintained at the reaction temperature for any desired period; however, we have found that there is a slight lowering of theyield if the reaction mixture is maintained at the reaction temperature for an excessively long period, such as, for example, about 16 hours.

In carrying out our reaction, we also prefer to employ an .excess of the t-alkoxide. Theoretically, two moles of alkyl nitrate, one mole of cyclic ketone and two moles of the t-alkoxide would be required; however, we prefer to employ an excessas indicated above, and we have employed and prefer to employ an excess up to about 65% over the amount theoretically required since we have found that such excess tends to increase the yield of the final product.

As mentioned above, we prefer to bring the reactants together in a particular manner since we have found that our preferred order of addition of reactants tends to increase the yield. We prefer to first add the cyclic ketone I to a solvent solution of the base and then add the alkyl nitrate to the mixture of cyclic ketone and base. We believe that in so adding the reactants, we tend to increase the yield by minimizing the tendency of unfavorable equilibrium conditions to form and minimizing the possible loss of alkyl nitrate due to decomposition through prolonged contactof-thenitra-te with the t-alkoxide. The following table gives results which indicate that the order of addition of reactants tends to increasce the yield of the final product. In'the experiments, the data for which are shown in the following table, the reaction was carried out at a temperature of 30 C. and a 10% excess of t-alkoxide was employed. All other conditions were the same in each experiment.

'1 Yield of 1,1,4,4-tetrabromo-1,4dinitrobutane.

The felling examples are offered to illustrate our invention; however, we do not intend to be limited to the specific procedures, materials, or conditions shown.

Rather, we intend to include within the scope of this application all equivalents obvious to those skilled in the art.

Example I A solution of 18.5 grams of potassium t-butoxide in 90 ml. of tetrahydrofuran was cooled to 30 C. and a solution of 4.2 grams of cyclopentanone in 60 ml. of tetrahdyrofuran was added dropwise over 30 minutes. Following addition of the cyclopentanone, a solution of 14.6 grams of amyl nitrate in 35 ml. of tetrahydrofuran was added dropwise over 30 minutes at the temperature of 30 C. When the addition of amyl nitrate was completed, stirring was continued for one hour as the mixture was allowed to warm to 25 C. A crude salt of dipotassium dinitrocyclopentanone precipitated from the solution and was removed by pressure filtration and Washed with tetrahydrofuran and ether. The crude salt was reprecipitated from a concentrated aqueous solution with 5 volumes of methanol and the purified salt then brominated by dissolving the salt in water and adding the aqueous solution rapidly at 0 C. to a solution of potassium hypobromite in 150 ml. of water. The product 1,1,4,4- tetrabromo-l,4-dinitrobutane crystallized and was separated by filtration and recrystallized from hexane to obtain 16.6 grams of the bromo compounds for a yield of 71.5%.

Example II The process described in Example I was repeated using cyclohexanone instead of cyclopentanone and the final product, 1,1,5,5-tetrabrorno-1,S-dinitrO-pentane was obtained in the amount of 13.0 grams for a yield of 54.5%.

Example 111 The process of Example I was repeated using cycloheptanone instead of cyclopentanone and the final product 1,1,6,6-tetrabromo-1,6-dinitrohexane was obtained in the amount of 13.21 grams for a yield of 53.8%.

Example IV The process of Example I was repeated using cyclooctanone instead of cyclopentanone and the final product 1,1,7,7-tetrabromo-1,7-dinitroheptane was obtained in the amount of 4.3 grams for a yield of 34%.

Example V The process of Example I was repeated using cyclobutanone instead of cyclopentanone and 1,1,3,3-tetrabromo-1,3-dinitropropane was obtained as the final product.

Example VI A suspension of 12.3 grams of potassium t-butoxide in 70 ml. of anhydrous ether was cooled to 30 C. and a solution of 4.2 grams of cyclopentanone in 70 ml. of anhydrous ether was added dropwise over a period of 30 minutes. When the addition of the cyclopentanone was completed, a solution of 14.6 grams of amyl nitrate in 33 ml. of anhydrous ether was added dropwise over a period of 30 minutes at a temperature of 30 C. Agitation of the reaction mixture was continued for one hour while the mixture was allowed to warm to 25 C. The product, dipotassium dinitrocyclopentanone was separated and reprecipitated as in Example I and then dissolved in 75 ml. of water. This solution was added rapidly at 0 to a solution of potassium hypobromite in 150 m1. of water. Crystalline 1,1,4,4-tetrabromo-1,4-dinitrobutane was separated and then recrystallized from hexane. The yield of 1,1,4,4-tetrabromo-1,4-dinitrobutane was 12.71 grams or 54.8%.

Example VII The process described in Example V was repeated except that ethyl nitrate was used in place of amyl nitrate.

4 The yield of 1,1,4,4-tetrabromo-1,4-dinitrobutane was 52.3%.

Now having described our invention, What we c1a1m1s:

1. A process for the production of the dipotassium salt of an u,a'-dinitrocyc1oaliphatic .ketone which comprises reacting a cyclic ketone with an alkyl nitrate in the presence of a potassium t-alkoxide in an inert alcoholfree medium.

2. A process for production of the dipotassium salt of an a,a'-dinitrocyclic ketone which comprises adding an alkyl nitrate to a mixture of a cycloaliphatic ketone and a potassium t-alkoxide in an inert alcohol-free medium.

3. A process for production of the dipotassium salt of an u,a-dinitrocyclic ketone which comprises adding an alkyl nitrate to a mixture of a cycloaliphatic ketone selected from the group consisting of cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone, and cyclooctanone and a potassium t-alkoxide in an inert alcohol-free medium.

4. A process for production of the dipotassium salt of an u,a-dinitrocyclic ketone which comprises adding a lower alkyl nitrate to a mixture of a cycloaliphatic ketone and a potassium t-alkoxide in an inert solvent selected from the group consisting of tetrahydrofuran, ether, toluene, and hexane while maintaining the reactants alcohol-free.

' alcohol-free medium at a temperature less than about 7. A process for the production of the dipotassium salt of an u,a'-dinitrocyclic ketone which comprises adding an alkyl nitrate to a mixture of a cycloaliphatic ketone and potassium t-butoxide in an alcohol-free medium.

8. A process for the production of the dipotassium salt of an a,u-dinitrocyclic ketone which comprises adding an alkyl nitrate to a mixture of a cycloaliphatic ketone and potassium 1,1-dimethylpropionoxide in an inert alcohol-free medium.

9. A process for the production of dipotassium 2,6- dinitrocyclohexanone which comprises adding amyl nitrate to a tetrahydrofuran solution of a mixture of cyclohexanone and potassium t-butoxide at a temperature of about -30 C.

10. A process for the production of dipotassium 2,7- dinitrocycloheptanone which comprises adding amyl nitrate to a tetrahydrofuran solution of a mixture of cycloheptanone and potassium t-butoxide at a temperature of about -30 C.

butanone and potassium t-butoxide at a temperature of about -30 C.

References Cited in the file of this patent Wieland et al.: Annalen, vol. 461, pp. 295-308 (1928).

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,868,838 January 13, 1959 Henry Feuer et ale It is herebj certified that error appears in the -printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Colmnn 2 line 65, TABLE II, for "Cyclopentanone and nitrate to base" read Cyclopentanone to base and nitrate an Signed and sealed this 2nd day of June 1959:

(SEAL) Attest:

KARL AXLINE ROBERT c. WATSON Commissioner of Patents Attesting; Oflicer 

1. A PROCESS FOR THE PRODUCTION OF THE DIPOTASSIUM SALT OF AN A,A''-DINITROCYCLOALIPHATIC KETONE WHICH COMPRISES REACTING A CYCLIC KETONE WITH AN ALKYL NITRATE IN THE PRESENCE OF A POTASSIUM T-ALKOXIDE IN AN INERT ALCOHOLFREE MEDIUM. 